The benefits of deep sleep
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Modern life has many causes of deteriorating shoulders & stiffness.
Use your PC smartphone in the same posture, tension caused by stress at work, disturbing your autonomous nerves, and using a pillow that is easy to strain your neck.
Straight neck may be caused by those with this symptom.
What is a straight neck?
The cervical spine naturally maintains a proper curve to support the head, but the chronic depression posture will lose the curve of the cervical vertebrae, causing a variety of neglects in the body such as headaches, shoulder & stiffness.